Life 103- week 3
Life 103- week 3 LIFE 103
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This 3 page Class Notes was uploaded by Alexis Darling on Friday February 5, 2016. The Class Notes belongs to LIFE 103 at Colorado State University taught by Jennifer L Neuwald; Tanya Anne Dewey in Fall 2016. Since its upload, it has received 10 views. For similar materials see Biology of Organisms-Animals and Plants in Biology at Colorado State University.
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Date Created: 02/05/16
Fungi: All are heterotrophs, meaning they consume organic carbon to grow. While they are most related to animals than to plants or other eukaryotes, they absorb nutrients from outside of their bodies, unlike animals. Nutrition: Most are Saprophytic, meaning they eat dead organic matter by way of excreting digestive enzymes, which break down the matter outside of their cells, then the small compounds are absorbed. Therefore they grow in and towards their food and lack stomachs. Body structure: Some are single celled (called “yeast”), but most are multicellular which allows them to expand to absorb more nutrients. Their cells grow end to end to make long filaments called hyphae which interweave to become bunches of mycelia. These thin branches are specialized for maximum surface area so that they absorb as much as possible. Their cell walls are made of chitin… Symbiotic relationships (both benefit): Mycorrhizae fungi grow into the roots of plants so that they absorb carbohydrates and other nutrients from the plants, but the plants also receive from fungi ions and minerals, which fungi are best at absorbing. Lichens photosynthetic microorganisms, either green algae or cyanobacteria, grow in a layer under lichen surface and supply carbon compounds or nitrogen to the fungi while the fungi protects the microorganisms Sexual or asexual life cycles Haploid spores come together in two steps: Plasmogamy cytoplasm from two parent mycelia come together as the nuclei remain separate the cells are called heterokaryons Karyogamy nuclei come together and officially make the cell diploid The diploid phase eventually undergoes meiosis, including the factors of crossing over and independent assortment for genetic diversity. Fungi Main Groups ● Chytrids unifying ancestors, still have flagella ● Zygomycetes live in all sorts of environments and have many different feeding methods ● Glomeromycetes responsible for mycorrhizae in 80% of plant species ● Ascomycetes called sac fungi due to their spores for sexual reproduction held in asci which collectively are contained in fruiting bodies called ascocarps ● Basidiomycetes fruiting bodies from sexual reproduction called basidiocarps Seedless Land Plants: All land plants with embryos called Embryophytes, which evolved to colonize areas and diversify. Sporopollenin durable layer found in plant spore walls to prevent zygotes from desiccation (drying out) as plants came out of their underwater environments onto dry land Land plants began as seedless nonvascular then developed into vascular plants to grow tall… Bryophytes: The seedless nonvascular plants Made up of 3 main groups: ? Liverworts ? Hornworts ? Mosses Five key traits: ● Alternation of generations 1. gametophyte haploid, multicellular growth; purpose= produce gametes by mitosis so that one female and one male gamete can form a sporophyte 2. sporophyte (formed by two gametes coming together) diploid, multicellular growth; purpose= produce haploid spores by meiosis to grow more gametophytes *spend most of life cycle in gametophyte stage (multicellular haploid plant) ● Multicellular, Dependent Embryos Once the male gamete has undergone fertilization with the female gamete, the embryo formed requires nutrients from the female gametophyte (site of fertilization). ● Sporangia to produce spores Sporangia are the organs in which the sporophyte produces walled spores through meiosis *spore walls made of sporopollenin for protection ● Multicellular Gametangia The gametophytes have female gametangia (archegonia) or male gametangia (antheridia) which produce gametes. Male gametangia releases the sperm, female gametangia maintains the egg and are the site of fertilization. ● Apical Meristems the tips of the roots and shoots must be apical meristems from which the cells grow out of and differentiate. Purpose= growth/elongation of roots and formation of leaves Other properties: cuticle waxy layer on epidermis to protect from desiccation stromata cells which form little holes in the surface of the leaf for gas exchange heterosporous the spores formed are either male (microspores) or female (megaspores); no one gametophyte can form both types of gametes Seedless Vascular Plants: 2 mains groups: ? Lycophytes club and spike “mosses” (not true moss because they have vascular structures) and quillworts ? Monilophytes ferns, horsetails, and whisk ferns Three key traits: ● Majority of life cycle spent as sporophytes ● Vascular tissue (like tubes) xylem for water and minerals phloem for food; sugars, amino acids, organic products ● Developed roots and leaves these roots have vascular tissues, unlike the Rhizoids of mosses, and keep them more strongly anchored Other properties: Sporophylls modified leaves that contain spore producing structures Sori (plural, singular=sorus) bunches of sporangia on the underside of sporophylls Sporangia location of meiosis, capsule that contains haploid spores Homosporous spores produced are all the same (not female or male) and all develop into bisexual gametophytes which produce both female and male gametes
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